The present invention generally relates to the identification of workpieces and more specifically to a method of identifying workstations that performed work on a workpiece.
It is known to provide a marking system that marks a finished workpiece to identify the model of the workpiece, the production run that produced the workpiece and/or the order of production of the workpiece. An example of such a marking process for a vehicle frame is disclosed in U.S. Pat. No. 5,202,836 to lida et al., which is assigned to the assignee of the present application. If a defect later appears in the workpiece, such a mark helps identify when the workpiece was finished, which provides some help in identifying the source of the defect. In a typical manufacturing operation, however, a plurality of workstations work on a workpiece. Moreover, there are typically a plurality of workstations that perform the same operation or process. Thus, a workpiece may, for example, have a particular drilling operation performed on it by one of a plurality of drilling machines. As a result, even if the particular drilling operation is identified as the source of a defect in the workpiece, the defect may have been caused by any one of the drilling machines. Conventional marking systems, such as the type identified above, fail to provide a mark or marks that can identify a particular workstation as having performed an operation on a particular workpiece.
Accordingly, there is a need in the art for a method of identifying workstations that performed work on a workpiece. The present invention is directed to such a method.